Intra-aortic balloon catheters are used in patients with left heart failure to augment the pumping action of the heart. The catheters, approximately 1 meter long, have an inflatable and deflatable balloon at the distal end. The catheter is typically inserted into the femoral artery, and moved up the descending thoracic aorta until the distal tip of the balloon is positioned just below or distal to the left subclavian artery. An air passageway for inflating and deflating the balloon extends through the catheter and is connected at its proximal end to an external pump. The patient's ECG may be used to produce balloon inflation in synchronous counter pulsation to the patient's heart beat.
Intra-aortic balloon therapy increases coronary perfusion, decreases the workload of the left ventricle, and allows healing of the injured myocardium. Ideally, the balloon should be inflating just as the aortic valve closes and deflating just prior to the onset of systole. When properly coordinated, the inflation of the balloon raises the patient's diastolic pressure, increasing the oxygen supply to the myocardium; and balloon deflation just prior to the onset of systole lowers the patient's diastolic pressure, reducing myocardial oxygen consumption.
Intra-aortic balloon catheters may also have a central passageway or lumen which can be used to measure aortic pressure. In this dual lumen construction, the central lumen may also be used to accommodate a guide wire to facilitate placement of the catheter, or may be used to infuse fluids, or to do blood sampling.
Typical dual lumen intra-aortic balloon catheters have an outer, flexible, plastic tube and a central tube therethrough formed of plastic tubing, stainless steel tubing, or wire coil embedded in plastic tubing. Polyurethane is used to form the balloon. Problems associated with current intra-aortic balloon catheter constructions are kinking of the outer tube, kinking of the central tube, and restriction of a blood flow to the legs caused by the position and size of the catheter in the artery.
It is an object of the present invention to provide an improved intra-aortic balloon catheter with a kink-free outer tube leading to reduced kinking of the air passage lumen.
It is another object of the present invention to provide an improved intra-aortic balloon catheter with a strong flexible kink-resistant central tube formed of a strong resilient, flexible, kink-resistant metal alloy tube.
It is another object of the present invention to provide an improved intra-aortic balloon catheter with an air passage lumen of increased cross section for greater air flow.
It is another object of the present invention to provide an improved intra-aortic balloon catheter of reduced outer diameter to decrease its resistance to blood flow in the descending aorta.